How to Fit Nonlinear Equations in MATLAB?

In summary, the conversation discusses the process of fitting nonlinear equations using MATLAB. The individual has data and wants to fit two equations with three parameters. They have tried using the cftool, but it can only fit one equation. They have also searched for other options and found a suggestion to use "MATLAB fitting system of equations." Further advice is given to search for this keyword to find more relevant results.
  • #1
Haorong Wu
418
90
TL;DR Summary
Fitting nonlinear equations with same parameters
Hello. I am trying to fit some nonlinear equations.

I have some data ##\vec \lambda, \vec n, \vec \kappa ##. Now I would like to use them to fit two equations $$n=n(\lambda ; \alpha, \beta, \gamma)$$ $$\kappa=\kappa(\lambda ; \alpha, \beta, \gamma)$$ where ##\alpha, \beta, \gamma## are the parameters to be fitted.

Which toolbox or command should I refer to?

I have tried cftool. But it can only fit one equation. I googled "Fitting nonlinear equations matlab". It seems most of the results are fitting one equation.

Looking for some advice, while I am keeping searching for other keywords.

Thanks!
 
Physics news on Phys.org

FAQ: How to Fit Nonlinear Equations in MATLAB?

How do I know if my data can be fit with a nonlinear equation?

There are a few ways to determine if your data can be fit with a nonlinear equation. One way is to plot your data and see if it looks like a curve rather than a straight line. Another way is to look at the relationship between your variables and see if it follows a known nonlinear function, such as exponential or logarithmic.

What is the best method for fitting nonlinear equations?

The best method for fitting nonlinear equations depends on the specific equation and data being used. Some common methods include least squares regression, non-linear least squares regression, and maximum likelihood estimation. It is important to choose a method that is appropriate for your data and provides the most accurate results.

Can I use Excel to fit nonlinear equations?

Yes, Excel has built-in functions for fitting linear and some common nonlinear equations. However, these functions may not be suitable for all types of data and equations. It is important to check for the assumptions and limitations of the Excel functions before using them for fitting nonlinear equations.

How do I interpret the results of a nonlinear equation fit?

The results of a nonlinear equation fit will typically include the equation’s parameters, such as the slope and intercept, and a measure of the fit's quality, such as the coefficient of determination (R-squared). The parameters can be used to describe the relationship between the variables, while the R-squared value indicates how well the equation fits the data.

What are some common challenges in fitting nonlinear equations?

Some common challenges in fitting nonlinear equations include choosing an appropriate model, dealing with a large number of parameters, and handling outliers or missing data. It is also important to be aware of any assumptions or limitations of the chosen method and to carefully interpret the results to ensure they are meaningful and accurate.

Similar threads

MATLAB How do I write this chua oscillator to an audio file in matlab?
Replies
5
Views
2K
MATLAB Fit with implicit nonlinear function - Matlab
Replies
1
Views
3K
Nonlinear Equation Fitting: Exploring Solutions
Replies
6
Views
902
MATLAB Solving the Duffing Equation with ODE45
Replies
1
Views
2K
MATLAB Suggestions for a non-linear fit model in Matlab
Replies
1
Views
2K
MATLAB Troubleshooting Best Fit Line and Distance Calculation in MATLAB
Replies
14
Views
3K
Best software to fit molecular spectroscopy data
Replies
1
Views
2K
MATLAB To what extent is the fit to experimental data good?
Replies
12
Views
3K
MATLAB [Matlab] Which is the good solution My vs. School - curve fitting?
Replies
2
Views
2K
MATLAB How to transform a plot to use a logarithmic scale?
Replies
9
Views
4K

Hot Threads

Recent Insights

Back
Top